For multi-million-Btu thermal energy facilities such as electric-power plant boilers and industrial furnaces, an attractive fuel is carbonaceous material suspended in a liquid slurry and, therefore, transportable through pipelines and by transport methods similar to those used for conveying fuel oil. The carbonaceous fuel material may be solid or liquid, but is dispersed in a liquid carrier. A typical slurry is a coal/water slurry. In this medium, coal can be transported and combusted with minimum material-handling and operational problems. Combustion of slurry, however, poses different problems as compared to the combustion of pulverized coal, oil or other discrete, carbonceous materials in a gaseous medium. Performance depends on how well and quickly the slurry is atomized, mixed with oxidant and heated to ignition temperature.
In high power density slagging combustion systems, such as that described in copending patent application Ser. No. 670,417 filed Nov. 13, 1984, now abandoned, a primary requirement is immediate ignition and stable combustion of particulate fuel, in a stable flame pattern, within a few milliseconds after the fuel enters the combustion chamber and closely adjacent the point where the fuel issues from the fuel injector. In such systems, as well as in conventional boilers and industrial furnaces, a need has existed for improved fuel-injection subsystems, capable of handling and injecting coal-water slurries in a manner such that ignition and combustion of the carbon content of the fuel occurs immediately, consistently and with maximum flame stability. These criteria require extreme comminution of the slurry into the smallest possible droplets and intimate mixing of the droplets with high temperature oxidant as promptly as possible after they enter the combustion chamber.
The present invention is particularly useful in the high power density, slagging combustion systems referred to above. However, its applicability is not so limited; it may be used to considerable advantage for the combustion of liquid slurries of solid carbonaceous fuel in substantially any apparatus, boiler, furnace or facility where it is desired to transport particulate fuel carried in a pumpable liquid from a fuel source or depot to the fuel combustion and heat utilization equipment.